Re: shift accidental in chord

[Mats Bengtsson]

Kieren MacMillan wrote:
> Hi Damian,
>
> Just to confirm... are you looking for
>
> \version "2.11.38"
> { \set Staff.extraNatural = ##t beses' bes' }
>
> i.e., to correct a previous accidental on the same note in the same bar?
>
> If not, please give a good reason for having both accidentals but no 
> "split stem", so we can better help you get Lilypond to do what you want.
My impression is that he wants something like
\version "2.10.0"
naturalplusflat = \markup { \natural \flat }
{
\once \override Accidental #'stencil =
     #ly:text-interface::print
  \once \override Accidental #'text = #naturalplusflat
 \once \override Score.AccidentalPlacement #'right-padding = #1.5
 <b' bes'>
}

Since <b bes> gives you two note heads, it's not completely impossible 
for the
musician to interpret this as a chord with a b natural and a b flat, but 
the
natural could also be interpreted as just a cancellation of a previous 
accidental.
One layout option that is less ambiguous is to have a split stem, which 
unfortunately
isn't supported in LilyPond today, even though
http://lists.gnu.org/archive/html/lilypond-user/2008-01/msg00208.html
gives something in that direction.

  /Mats